The current connection between transformer bushing and transformer/reactor in an HVDC (High Voltage Direct Current) converter transformer or smoothing reactor is usually protected by an insulation system.
A high voltage insulation system for bushing connections of HVDC transformers and smoothing reactors is for example known from the European Patent No. 0285895. The patent discloses a bushing with its conductor connected to the transformer conductor inside a screen (a shielding electrode). The current connection inside the shielding electrode is enclosed by solid insulation barriers situated in the transformer oil, which makes up the enclosing insulation system.
The method of increasing electrical withstand strength against AC stress in transformer oil by subdividing the oil volume around an electrode is also well known.
According to a first aspect the present invention seeks to provide an improved insulation system for very high voltages. According to a second aspect the invention seeks to provide an improved method of manufacturing such a system.